Controlling mechanism for pneumatic-despatch-tube apparatus.



A. W. PEARSALL. CONTROLLING MECHANISM FOR PNEUMATIC DESPATCH TUBE APPARATUS. APPLICATION FILED JULY 15, 1912.

LU9K559 Patented May19,1914.

2 SHEETS-SHEET 2.

i i g I g I i I glllllllllllllfll l/vi tmcooeo UMTED OFFICE;

Annnnr w. fEABSALL, or nown'nn, MASSACHUSETTS, Assieno'n 'ro rntntnmson conrAnY, on nosron, MASSACHUSETTS, A conronArron or new annsnv.

con'rnonmns mncHAnrsn: iron. rnnumArrc-nn'srnrcn-rnnn APrAR'A'rUs.

neonate.

Specification of Letters Patent. *2 Patented lway 19, 1914.. Application filed July 15', 1912. Serial no. rea m;

To all whom it may concern:

Be it known that ll, ALBERT W. PnAisALL, of Lowell, in the county of Middlesex and State of Massachusetts, have invented certain new and useful improvements in Controlling Mechanism for Pneumatic-De spatch-Tube Apparatus, of which the following is a specification.

My invention relates to the control and the automatic starting of an electric motor or motors when used to operate exhausters or positive pressure blowers used to generate a fluid pressure no greater than that used in the transmission tubes of a\pneu matic despatch tube system, and at the same time to supply fluid pressure, so that it shall be instantaneously ready for transmitting purposes, all with the use of substantially the minimum amount of electric force.

The main object of this invention is to provide an ever ready transmitting force, and with the expenditure of practically more power than that required to perform the transmitting service. This is in contradiction to present power generating equipments operated with electric motors intended to economize in the operating expense of pneumatic 'despatch tube systems; first for eX- ample, in that type using small positive blowers or exhausters which are operated with series motors which start and stop. {Such systems are usually of limited capacity since only small motors will permit of their being started by having the current thrown in them at once, and they are also limited to the use ofsmall blowers or exhausters, as the sudden starting of this class of machinery from rest requires the use of "is too great to permit of such use where rapid service is required. The present sys tem having, as it' does, for its main object that above referred to, is further essentially a different from the type of systems otpneumatic despatch tubes which are operated by a pressure in excess of that of the atmosphere and which are provided with storage tanks in which compressed air is stored at a pressure greater than that used to operate the transmission tubes, the said pressure being reduced byme'an's of a reducing valve before being used in the transit tubes. It will readily be seen that all power expended in com ressing this air to a pressure greater than t at required for transmission pur poses is an expenditure of energy without useful effect and, therefore, does notpermit of the economy of power at which my in-- vention aims.

Another object of my invention is to provide a power equipment that will be sufficiently elastic to meet the maximum demands of the service for any number of lines and any size transmission tube, at the same time permitting, when no service is required, "the use of what is technically known as a closed system without an increase ofpressure. This cannot now be accomplished with asingle unit as the range ofspecd variation of the operating motor is limited by reason of electrical incficiency. A

The general nature of my invention is as follows: The transmission tubes or circuits of a pneumatic despatch tube system equipped with any of the well known power control devices (devices which automatically estab lish a flow of air in the transit tube when carriers are introduced and "automatically arrest the flow of air in such transit tube upon delivery ofthe last carrier in transit) are connected to a suitable supply pipe, which is connected, according to the nature of the system, to either the compression or vacuum side of the exhausters or blowers.

These exhausters or blowers are oper'atively connected to electric motors preferably of the variable speedshun't field control type. One exhauster or blower with its motor is operated at its minimum speed, when no carriers are in transit; the other exhauster or blower and its motor being normally substantially at rest and only in operation when the demands of the transmission service exceed the capacity of the power unit normally in operation. The speed, of the motors op erating these power units is controlled by field regulating rheostat's actuated by the fluctuations in the fluid pressure generated primarily by the normally operating power unit; and secondarily, by the fluctuations in the fluid pressure generated by both power I or controlling rheostat of each power unit is connected to a portion of the supply pipe which is separated by a check valve from the power unit which is normally at rest, so that there is provided a supply of motive power to "the cylinder of the controlling rheostat of the motor of the power unit normallyat rest to the end that the latter unitneed not normally be started with a weakened field. This check valve also prevents the force generated by the power unit normally in operation from operating the unit at rest or offering resistance when it is being started. To insure that the power unit intended to be normally in operation is so controlled, a counter balance on the piston rod of the mechanism used to operate the field controlling rheostat of the motor ofthis unit is made slightly heavier than that on the piston of the mechanism used to operate the field controlling rheostat of the motor used to operate the power unit normally at rest.

In the accompanying drawings which illustrate a preferred form of construction embodying my invention: Figure 1 is a front elevation of the controlling panels showing their connection with the operating machinery, with each other and with the main electric feed wires. Fig. 2 is a front sectional elevation of the cylinder and piston arranged to operate the speed controlling rheostat when a fluid pressure in excess of that of the atmosphere is used to operate the despatch tube system. Fig.3 shows a modified form of a circuit closing means adapted to be substituted for plate B and contact posts 13 and B Like letters of reference refer to like parts throughout the several views.

In Fig 1, A is a drum to which the several lines of the pneumatic despatch tube system are connected and which is in turn connected with the' blower A by the pipe A the blower A being adapted to be driven by the motor A. To the drum A is also connected a branch T A and controlling communication with the T A is a check valve A in which the flap valve A is movably mounted and when not seated can swing in the direction shown in dotted out line, to the. check valve A is attached the pipe A connecting with the blower A which is adapted to be driven by the motor A The blower A driven by its motor A" is to be considered as the primary power unit as shown in Fig.

1 and the blower A and its motor A as' the apparatus mounted on the secondary controlling panel Z. Mounted on the primary controlling panel X is the cylinder D and upon the secondary panel Z the cylinder I D both being in communication with the drum A through the pipe A and T D. VVithin'the cylinder D is the piston D. at-

controlling rheostat B by the insulator link D and within the cylinder D is the piston 13 attached to the piston rod D which car ries at its lower end the adjustable weight D and is connected at its upper end with the field controlling arm 13 by the insulator link D Upon the primary controlling panel X isalso mounted the manually operated starting rheostat B and the motor fieldjcontrolling rheostat 13 which are connected by the wire 13*, without resistance, and by the wires B B B, B and B with increasing. resistance, the manually operated motor starting rheostat B being placed in circuit with .the source of electric supply by the double pole switch X and the wires E and B and the motor A being connected to the starting rheostat B by the shunt field and armature wire C and the armature wire C; the shunt field wire C connecting the field controlling rheostat B and the motor A".

Carried upon the field controlling rheo.

stat arm B and insulated therefrom is the contact plate B adapted to contact with the contact posts 13 and B completing a circuit in the main line solenoid switch E through double pole switch X, wire E, contact post B contact plate B contact post B wire E solenoid E and wire E When the solenoid E is energized, its armature carrying the contact plate E rises and by coming into engagement with contact posts E and E completes a circuit in the solenoid motor starting rheostat B (which is mounted on the secondary controlling panel Z) in the following manner: Assuming that the double pole switch Z is closed in the main electric supply circuit, current will flow through the wire E contact post E, contact plate E contact post E wire E, solenoid F of the solenoid motor starter B via wire E again to the double pole switch Z; the solenoid F of the solenoid motor starter. B being energized and its armature F, which is connected to the contact lever 13 being caused to move upward,

rotating the contact lever 13 on its pivot B Theaspeed of this movement is con; trolled through the connection to the piston rod G of (the dashpot G. The solenoid motor starting rheostat B is connected by six wires to the field controlling rheostat 13 m, identically the same way as shown by wires 13*, B B B, B and B on primary panel X. The-motor A is connected to the solenoid motor starting rheostat B by the shunt field wire C and the armature wire inmate C and with the field controlling rheostat B by the wire C.

the introduction of some field resistance through connection made by the wires B, f B, B B and B, causing the blower, which is operated in this instance as an exhauster, to create a pressure below that of the atmosphere sutficient to overcome the counter weight D causing the piston D in the cylinder D to rise and through its piston-rod D and the insulator link lU connecting this rod with the contact arm B or the field controlling rheostat B thereby causes said arm to assume a position gorresponding to that in which is shown the arm B of the field controlling rheostat B of the secondary panel Z. The adjustable counterweight D of the primary panel Xi's slightly heavier than the adjustable counterweight l)", and hence since both the cylinders l) I and D are connected by the pipe A, the

piston D in the cylinder D will also, under the conditions stated, have risen, causing its piston rod D with the insulator link D connecting the contact arm B of the field controlling rheostat B and, of course, to assume the position shown on the secondary panel Z inhig; l. The primary power unit, being controlled by the apparatus mounted on the panel X, will now be operating under L its minimumservice condition with the contact arm B of the field controlling rheostat B rotated clockwise to the extent of its movement in this direction. If one or incire of the transmission tubes which are connected to the drum A, and which are controlled by timing valves normally closed when not in use, he placed in pperation by the opening of the timing valve, or valves, to which they are connected, it will be seen that a departure from the pressure belowits pivot 18 toward the position in which this arm is shown inhig. l, causing the motor A to increase in speed by cutting in resistance in its field, and causing the blower A, which it operates, to displace a quantity of air sutlicient to meet the service requirement at the pressure determined by the adjustable weightD". lit theservice load condit ons continue to increase by the use of additional transit tubes, the contact arm B carrying the contact plate B will finally assume the position shown in Fig. l, causing its contact plat-e13" to contact with the contact posts B and B thereby completing the circuit adapted to energize the solenoid of the main line solenoid switch 1E; causing its armature to rise carrying the contact plate E into engagement with contact posts E and E and thereby closing the circuit adapted to energize the solenoid F of the solenoid motor starting rheostat 18 The armature l of the latter, which is connected to the contact lever B therefore rises, rotating the contact lever'B on its pivot B and causing the motor 1' 11 and blower A to start and speed up; displacing a quantity of air suficient to overcome the slippage of the blower at the pressure for which the adjustable weight D is set, which pressure is slightly less than that carried by the primary power unit so as to insure that the field controlling contact arm B? of the field controlling rheostat B will be maintained in the strong field position when the motor A is automatically thrown in by the solenoid motor starter B. The operation of additional transit lines will now further break the vacuum which will cause the piston in the cylinder D, which is fixed to the piston rod D and which is connected to the field controlling rheostat arm B by' the insulator link D to move downward under the influence of the adjustable weight 1), causing the contact arm B to rotate in car the direction to cut in resistance in the weight. The air thus being displaced will be drawn through the check valve casing A, the flap valve A being unseated and both blowers A and A will then be displacing a quantity of air suficient for the operation of the transmission tube lines that are delivering air to the drum A by reason of the opening of their controlling valves; and this air will be at a pressure determined by the adjustable weight D. lit is apparent that as closure of the controlling valves of the transmission-tubes take place, a restriction of the flow of air into the drum A will occur and, owing to the displacement of the blowers at the speed at which they are being driven, an increase of pressure below that of the atmosphere will be established; causing the piston l) in the cylinder 1) of the secondary panel Z to rise and, through its connection with the field controlling rheostat arm B cause it to rotate in the 'CllIGCt-IOII to assume the positlon shown in Fig. 1, cutting out resistance in the field of the motor A and causing the latter and the blower A driven thereby to slow down. Through the closure of enough transmission tube controlling valves blower A will have its speed reduced to its minimum and at such time the field controlling contact arm B 'of the secondary panel Z will be in the position shown in Fig. 1 and the field controlling contact arm B of the primary controlling panel X will be in the position in which this part is shown in Fig. 1, which will maintain the primary power unit in operation at its maximum. A further closure of transmission tube controlling valves will result in increasing the vacuum, or in other words the efiective pressure below that of the atmosphere, suificient to cause the piston D to begin to ascend against the resistance ofiered by the adjustable weight D and through its connect-ion to rotate clockwise the field controlling contact arm B causing the maintaining circuit in the main line solenoid switch to be broken by the disengagement of contact plate B from contact posts B and B and thus deener- 'gizing the solenoid E; permitting its armature carrying the contact E to fall and thereby break the energizing circuit of solenoid F of the solenoid motor starter B 7 to ascend to its uppermost travel and,v through its connection with the contact arm 13 of the field controlling rheostat B to cut out resistance in the field circuit of the motor A to cause the latter to operate, together with the blower A which it drives, at its minimum speed. In general, therefore, it will be seen that I have provided a system comprising a' plurality of power units which are adapted to co-act under determined 'ventage conditions of the conduit or system in general, to maintain a flow of air through said conduit or drum A; the latter serving in efiect as a reservoir for the plurality of transit tubes used in the system.

lhe pistons D and D together with their associated parts and respective rheostats, together constitute automatic means for variablycontrolling the speed at which the respective power units are operated, in accordance with service conditions in the system.

The check valve proper A constitutes, in the preferred construction, a provision for insuring against areverse operation of one of the power units by another of the same; although it is obvious that various other provisions adapted to accomplish the same purpose might be employed to this end.

In the patent to Fordyce and Jennings, 1,009,400, dated November 21, 1911, there is disclosed a system in which it was aimed to maintain a predetermined working vacuum and to this end fiuid pressure controlled means was provided, the actuation of which was adapted to effect the automatic cutting in or cutting out of separate motors in a series of the same.

I am aware that in the patent to Dunbar, 977,079, dated November 29, 1910, a mechanism was described which in certain respects is not dissimilar to certain portions of the herein described apparatus, but it will be noted that in the Dunbar construction but a single motor or power unit is employed, while in the present case a plurality of motors are utilized, as in the said Patent 1,009,400.

My present construction possesses material advantages over either of the constructions described in the patents just referred to in that the change in eflort or force exerted to displace air through the'conduit is efi'ected very gradually and through a great range without unduly multiplying the number of motors involved and without using a single motor, which obviously cannot be economically operated through a wide range of speeds.

The present system is primarily designed to efi'ect economy of'operation, and this, it is believed, the system accomplishes to the maximum. Y

Having thus described the nature of my invention and set forth a construction embodying the same, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A pneumatic despatch tube system comprising a conduit, a plurality of power units adapted to co-act to jointly maintain a flow of air through said conduit, and automatic means for variably controlling the speed at which the respective power units are operated in accordance with service conditions in said system, said system including provisions for insuring against a reverse operation of one of said power units by another of the same.

2. A pneumatic despatch tube system com- 7 prising a conduit, a plurality of power units one at least of which is normally roperatively connected to said conduit, and adapted to maintain a fiow of air therethrough, means movable to establish communication between a second of said power units and said conduit, 1n accordance with service conditions 3. A pneumatic despatch tube system comprising a conduit, a plurality of power units one at least of which is normally operatively connected to said conduit,*and adapted to maintain a flow of air therethrough, means movable to establish communication between a second of said power units and said conduit, in accordance with service conditions in said system, and means for variably controlling one at least of said power units in accordance with said conditions.

A. A pneumatic despatch tube system comprising a conduit, a plurality of power units one at least of which is normally operatively connected-to said conduit, and adapted to maintain a How of air therethrough, means movable to establish communication between a second of said power units and said conduit, in accordance with service conditions in said system, and separate means for in-" dividually controlling said power units in accordance with said" conditions.

{3. A pneumatic despatch tube system comprising a conduit, a plurality of power units adapted to co-act to jointly establish a flow of air through said conduit, and automatic means for variably controlling the-speed at i which the respective power units are oppressure and that first mentioned.

erated in accordance with service conditions in said system, saidsystem including provisions for rendering substantially inoperative one of said power units when a determined pressure is established in said conduit, said provisions leaving portions at least of said automatic means tree to variably control another of said power units in accordance with said service conditions so long as the pressurefin said conduit ranges between a second predetermined pressure and that first mentioned.

6. A pneumatic despatch tube system comprising a conduit, a plurality of power units adapted to co-act to jointly establish a How of air through said conduit, and automatic 'means for variably controlling the speed at which the respective power units are operated, in accordance with service conditions in said system, said system including provisions for rendering substantlally inoperative one of said power units when a determined pressure is established in said conduit, said provisions leaving portions at least of said automatic means free to variably control another of said power units in accordance with said service conditions at least so long as the pressure in said-conduit ranges "between a second predetermine 7. A pneumatic des atch tube system comprising a conduit, a p urality of power units tomatic means for variably controlling the speed at which the respective power units are operated, a portion of said automatic means being operative to variably control one of said power units after another portion of said means has substantially ceased to variably control another of said power units.

9. A pneumatic despatch tube system comprising a conduit, means for maintaining a determined flow of air under a determined pressure through said conduit under determined ventage conditions in the latter, and separate, independently acting means for variably changing said How of air while substantially maintaining said determined pressure, in accordance with changes in said ventage conditions.

10. A pneumatic despatch tube system comprising a conduit, means, including a power unit, for maintaining a determined flow of air under a determined pressure through said conduit under determined ventage conditions in the latter, and separate, independently acting means, including a second power unit, for variably changing said flow of air, while substantially maintaining said determined pressure, in accordance with changes in said ventage conditions.

11. A pneumatic despatch tube system comprising a conduit, a plurality of power units one of which is adapted to establish and maintain a flow of air through said conduit and a second of which is adapted to augment said flow of air, fluid pressure controlled means for automatically controlling the first of said power units, means for variably controlling the second of said power units in accordance with service conditions in said system, and connections between said two means and said conduit, one of said means having a tendency to respond to a change in fluid pressure in said conduit before the other of said means.

12. A pneumatic despatch tube system comprising a conduit, a plurality of power units one of which is adapted to establish and maintain a flow of air through said conduit and a second of which is adapted to augment said flow of air, fluid pressure controlled means for automatically variably controlling the first of said power units,

means .for variably controlling the second of said power units in accordance with servname to this specification in the presence ice conditions in said system, and conneoof'two subscribing witnesses, this 12th day tions between said two means and said conof July 1912.

duit, one of said means having a tendency ALBERT W. PEARSALL. 5 to respond to a change in fluid pressure in VVitnesses: 1 1

said conduit before the other of said means. M. G. MACMILLAN,

In witness whereof, I have signed my ISAAC KRAFSUR. 

